Groove Diameter 0.7-0.9 inches This suction cup shower holder features an adjustable groove to secure your existing shower head. It is suitable for shower hoses with a bottom diameter between 0.7 and 0.9 inches (18-23 mm). Not suitable for shower hoses with a bottom diameter greater than or equal to 0.9 inches (23 mm). Measurements are recommended before purchase. Easy Installation, No Drilling Required: This adjustable suction cup shower holder installs in 1 second. No drilling or bolts are required. This handheld shower holder is sturdy, waterproof, and rustproof, and will not damage walls or leave marks after removal. Waterproof Material: This suction cup shower holder is made of engineering-grade ABS plastic, which is waterproof, rustproof, and corrosion-resistant, durable, and can be used for a long time even in humid bathroom environments. Adjustable Angle and Height: The rotating design allows you to easily adjust the shower angle to 70 degrees. The suction cup is detachable and replaceable. You can install the handheld shower head or bidet head anywhere you need, high or low, inside or outside the bathtub. It's especially suitable for wives, children, or parents who can't reach the showerhead. Usage tips: This powerful wall-mounted shower head holder is best suited for smooth, non-porous surfaces such as glass, mirrors, tiles, polished metal, and plastic panels. The suction cup is not suitable for uneven or bumpy surfaces.